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Sun Y, Tang L, Wu C, Wang J, Wang C. RSK inhibitors as potential anticancer agents: Discovery, optimization, and challenges. Eur J Med Chem 2023; 251:115229. [PMID: 36898330 DOI: 10.1016/j.ejmech.2023.115229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 02/19/2023] [Accepted: 02/20/2023] [Indexed: 02/27/2023]
Abstract
Ribosomal S6 kinase (RSK) family is a group of serine/threonine kinases, including four isoforms (RSK1/2/3/4). As a downstream effector of the Ras-mitogen-activated protein kinase (Ras-MAPK) pathway, RSK participates in many physiological activities such as cell growth, proliferation, and migration, and is intimately involved in tumor occurrence and development. As a result, it is recognized as a potential target for anti-cancer and anti-resistance therapies. There have been several RSK inhibitors discovered or designed in recent decades, but only two have entered clinical trials. Low specificity, low selectivity, and poor pharmacokinetic properties in vivo limit their clinical translation. Published studies performed structure optimization by increasing interaction with RSK, avoiding hydrolysis of pharmacophores, eliminating chirality, adapting to binding site shape, and becoming prodrugs. Besides enhancing efficacy, the focus of further design will move towards selectivity since there are functional differences among RSK isoforms. This review summarized the types of cancers associated with RSK, along with the structural characteristics and optimization process of the reported RSK inhibitors. Furthermore, we addressed the importance of RSK inhibitors' selectivity and discussed future drug development directions. This review is expected to shed light on the emergence of RSK inhibitors with high potency, specificity, and selectivity.
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Affiliation(s)
- Ying Sun
- Department of Respiratory and Critical Care Medicine, Targeted Tracer Research and Development Laboratory, Institute of Respiratory Health, Frontiers Science Center for Disease-related Molecular Network, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan, China; State Key Laboratory of Biotherapy and Cancer Center, Department of Respiratory and Critical Care Medicine, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan, China; Precision Medicine Key Laboratory of Sichuan Province & Precision Medicine Research Center, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan, China
| | - Lichao Tang
- Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Evanston, 60208, IL, United States
| | - Chengyong Wu
- Department of Respiratory and Critical Care Medicine, Targeted Tracer Research and Development Laboratory, Institute of Respiratory Health, Frontiers Science Center for Disease-related Molecular Network, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan, China; Precision Medicine Key Laboratory of Sichuan Province & Precision Medicine Research Center, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan, China
| | - Jiaxing Wang
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, 38163, Tennessee, United States
| | - Chengdi Wang
- Department of Respiratory and Critical Care Medicine, Targeted Tracer Research and Development Laboratory, Institute of Respiratory Health, Frontiers Science Center for Disease-related Molecular Network, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan, China.
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A natural small molecule induces megakaryocytic differentiation and suppresses leukemogenesis through activation of PKCδ/ERK1/2 signaling pathway in erythroleukemia cells. Biomed Pharmacother 2019; 118:109265. [DOI: 10.1016/j.biopha.2019.109265] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2019] [Revised: 07/10/2019] [Accepted: 07/24/2019] [Indexed: 01/04/2023] Open
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Zerumbone and Kaempferol Derivatives from the Rhizomes of Zingiber montanum (J. Koenig) Link ex A. Dietr. from Bangladesh. SEPARATIONS 2019. [DOI: 10.3390/separations6020031] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Zingiber montanum (J. Koenig) Link ex A. Dietr. (Zingiberaceae) is known as “Banada” in Bangladesh, and the rhizomes are frequently used in traditional medicines for the treatment of constipation, dyspepsia, flatulence, stomach bloating, and as mosquito repellant. In this study, dried rhizomes were extracted successively with 95% and 50% ethanol and the combined extract was then subjected to various column chromatographic methods to isolate one sesquiterpenoid derivative, zerumbone (1) and five kaempferol derivatives, i.e., kaempferol 3-O-methyl ether (2), kaempferol 3-O-α-rhamnopyranoside (3), kaempferol 3-O-α-(4”-O-acetyl)rhamnopyranoside (4), kaempferol 3-O-α-(3”-O-acetyl)rhamnopyranoside (5), and kaempferol 3-O-α-(3”,4”-di-O-acetyl)rhamnopyranoside (6). All compounds except 1 were isolated for the first time from the title plant.
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Mina SA, Mohamed SA, Melek FR, Abd El-Khalik SM. LC-ESI-MS/MS profiling of alkaloids and antiproliferative activity of Pachypoduim lamerei drake leaves. Nat Prod Res 2019; 34:1292-1296. [PMID: 30676770 DOI: 10.1080/14786419.2018.1556264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In the present study, evaluation of the antiproliferative activity of Pachypodium lamerei Drake leaves (family Apocyaceae) against human breast cancer cell lines MDA-MB-231 was done for the total methanolic extract, crude alkaloidal mixture and ursolic acid using the MTT colorimetric assay. The methanolic extract showed the strongest antiproliferative activity followed by ursolic acid and crude alkaloidal fraction with an IC50 equal to 6.2, 14.55 and 56.3 µg/ml respectively compared to oleocanthal. It is the first record for the LC/ESI-MS/MS alkaloidal profiling of the leaves of P. lamerei. Seven alkaloids were tentatively identified according to their fragmentation patterns. Four alkaloids were related to the parent indole class and two alkaloids belong to the quinoline class in addition to one steroidal alkaloid with a pregnan nucleus. Phytochemical investigation of the methanolic extract led to the isolation of three triterpenoidal compounds including ursolic acid, 11,12-didehydroursolic acid lactone and ursolic acid lactone.
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Affiliation(s)
- Suzan A Mina
- Pharmacognosy Department Faculty of Pharmacy, Helwan University, Cairo, Egypt
| | - Sohair A Mohamed
- Pharmacognosy Department Faculty of Pharmacy, Helwan University, Cairo, Egypt
| | - Farouk R Melek
- Chemistry of Natural Compounds Department, National Research Center, Giza, Egypt
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Reipas KM, Law JH, Couto N, Islam S, Li Y, Li H, Cherkasov A, Jung K, Cheema AS, Jones SJM, Hassell JA, Dunn SE. Luteolin is a novel p90 ribosomal S6 kinase (RSK) inhibitor that suppresses Notch4 signaling by blocking the activation of Y-box binding protein-1 (YB-1). Oncotarget 2014; 4:329-45. [PMID: 23593654 PMCID: PMC3712578 DOI: 10.18632/oncotarget.834] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Triple-negative breast cancers (TNBC) are notoriously difficult to treat because they lack hormone receptors and have limited targeted therapies. Recently, we demonstrated that p90 ribosomal S6 kinase (RSK) is essential for TNBC growth and survival indicating it as a target for therapeutic development. RSK phosphorylates Y-box binding protein-1 (YB-1), an oncogenic transcription/translation factor, highly expressed in TNBC (~70% of cases) and associated with poor prognosis, drug resistance and tumor initiation. YB-1 regulates the tumor-initiating cell markers, CD44 and CD49f however its role in Notch signaling has not been explored. We sought to identify novel chemical entities with RSK inhibitory activity. The Prestwick Chemical Library of 1120 off-patent drugs was screened for RSK inhibitors using both in vitro kinase assays and molecular docking. The lead candidate, luteolin, inhibited RSK1 and RSK2 kinase activity and suppressed growth in TNBC, including TIC-enriched populations. Combining luteolin with paclitaxel increased cell death and unlike chemotherapy alone, did not enrich for CD44+ cells. Luteolin’s efficacy against drug-resistant cells was further indicated in the primary x43 cell line, where it suppressed monolayer growth and mammosphere formation. We next endeavored to understand how the inhibition of RSK/YB-1 signaling by luteolin elicited an effect on TIC-enriched populations. ChIP-on-ChIP experiments in SUM149 cells revealed a 12-fold enrichment of YB-1 binding to the Notch4 promoter. We chose to pursue this because there are several reports indicating that Notch4 maintains cells in an undifferentiated, TIC state. Herein we report that silencing YB-1 with siRNA decreased Notch4 mRNA. Conversely, transient expression of Flag:YB-1WT or the constitutively active mutant Flag:YB-1D102 increased Notch4 mRNA. The levels of Notch4 transcript and the abundance of the Notch4 intracellular domain (N4ICD) correlated with activation of P-RSKS221/7 and P-YB-1S102 in a panel of TNBC cell lines. Silencing YB-1 or RSK reduced Notch4 mRNA and this corresponded with loss of N4ICD. Likewise, the RSK inhibitors, luteolin and BI-D1870, suppressed P-YB-1 S102 and thereby reduced Notch4. In conclusion, inhibiting the RSK/YB-1 pathway with luteolin is a novel approach to blocking Notch4 signaling and as such provides a means of inhibiting TICs.
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Affiliation(s)
- Kristen M Reipas
- Laboratory for Oncogenomic Research, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada
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Pandurangan N, Bose C, Banerji A. Synthesis and antioxygenic activities of seabuckthorn flavone-3-ols and analogs. Bioorg Med Chem Lett 2011; 21:5328-30. [DOI: 10.1016/j.bmcl.2011.07.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Revised: 06/18/2011] [Accepted: 07/06/2011] [Indexed: 10/18/2022]
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In vitro activity of dietary flavonol congeners against human cancer cell lines. Eur J Nutr 2011; 51:181-90. [PMID: 21598030 DOI: 10.1007/s00394-011-0204-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Accepted: 04/29/2011] [Indexed: 10/18/2022]
Abstract
BACKGROUND Flavonoids have physiological activity and a variety of pharmacological properties, including anticancer activity in vitro, but structure-anticancer activity relationships are unclear. AIM The objectives of this work were to investigate the activity of dietary flavonol congeners against cell lines derived from human solid tumours and to examine whether the in vitro activity was associated with specific structural feature(s) of the molecules. METHODS Antiproliferative activity of the flavonol congeners was investigated against eight different human cancer cell lines representing different types of human solid tumour, using the sulforhodamine B (SRB) assay in accordance with the instructions published by the NCI. Cell cycle perturbations caused by the congeners were monitored by flow-cytometric analysis of DNA stained with propidium iodide. RESULTS Most of the flavonols examined had weak antiproliferative and cytotoxic activity. Of all the flavonol congeners tested peracetylated tiliroside found to be the most powerful, with significant antiproliferative and cytotoxic activity. Most flavonols induced similar cell cycle perturbations, whereas induction of apoptosis was significant only for cells treated with peracetylated tiliroside. CONCLUSIONS These findings indicated that the -OH groups of aromatic ring B were not linked to the cytotoxic and antiproliferative activity of the tested flavonols whereas peracetylation of the glycosides resulted in moderate improvement. In contrast, acetylation of tiliroside esterified with coumaric acid at position 5 of the sugar moiety greatly improved the activity of this congener. Overall, the results of this study suggest a critical role of sugar moiety substituents in the anticancer activity of the flavonols.
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Huang HQ, Li HL, Tang J, Lv YF, Zhang WD. A new aurone and other phenolic constituents from Veratrum schindleri Loes. f. BIOCHEM SYST ECOL 2008. [DOI: 10.1016/j.bse.2008.03.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Veitch NC, Grayer RJ. Flavonoids and their glycosides, including anthocyanins. Nat Prod Rep 2008; 25:555-611. [DOI: 10.1039/b718040n] [Citation(s) in RCA: 216] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Smith JA, Maloney DJ, Hecht SM, Lannigan DA. Structural basis for the activity of the RSK-specific inhibitor, SL0101. Bioorg Med Chem 2007; 15:5018-34. [PMID: 17512736 DOI: 10.1016/j.bmc.2007.03.087] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2007] [Revised: 03/29/2007] [Accepted: 03/29/2007] [Indexed: 11/19/2022]
Abstract
Inappropriate activity of p90 ribosomal S6 kinase (RSK) has been implicated in various human cancers as well as other pathologies. We previously reported the isolation, characterization, and synthesis of the natural product kaempferol 3-O-(3'',4''-di-O-acetyl-alpha-l-rhamnopyranoside), termed SL0101 [Smith, J. A.; Poteet-Smith, C. E.; Xu, Y.; Errington, T. M.; Hecht, S. M.; Lannigan, D. A. Cancer Res., 2005, 65, 1027-1034: Xu, Y.-M; Smith, J. A.; Lannigan, D. A.; Hecht, S. M. Bioorg. Med. Chem., 2006, 14, 3974-3977: Maloney, D. J.; Hecht, S. M. Org. Lett., 2005, 7, 1097-1099]. SL0101 is a potent and specific inhibitor of RSK; therefore, we performed an analysis of the structural basis for the inhibitory activity of this lead compound. In in vitro kinase assays we found that acylation of the rhamnose moiety and the 4', 5, and 7-hydroxyl groups are responsible for maintaining a high affinity interaction of RSK with SL0101. It is likely that the hydroxyl groups facilitate RSK binding through their ability to form hydrogen bonds. To determine whether the SL0101 derivatives were specific for inhibition of RSK we analyzed their ability to preferentially inhibit the growth of the human breast cancer line, MCF-7, compared to the normal human breast line, MCF-10A. We have previously validated this differential growth assay as a convenient readout for analyzing the specificity of RSK inhibitors [Smith, J. A.; Maloney, D. J.; Clark, D. E.; Xu, Y.-M.; Hecht, S. M.; Lannigan, D. A. Bioorg. Med. Chem., 2006, 14, 6034-6042]. We found that acylation of the rhamnose moiety was essential for maintaining the selectivity for RSK inhibition in intact cells. Further, the efficacy of SL0101 in intact cells is limited by cellular uptake as well as possible hydrolysis of the acetyl groups on the rhamnose moiety by ubiquitous intracellular esterases. These studies should facilitate the development of a RSK inhibitor, based on the SL0101 pharmacophore, as an anti-cancer chemotherapeutic agent.
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Affiliation(s)
- Jeffrey A Smith
- Center for Cell Signaling, Department of Pathology, University of Virginia, Charlottesville, VA 22908, USA
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Shan M, O'Doherty GA. De novo asymmetric syntheses of SL0101 and its analogues via a palladium-catalyzed glycosylation. Org Lett 2006; 8:5149-52. [PMID: 17048865 PMCID: PMC2529254 DOI: 10.1021/ol062076r] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The enantioselective syntheses of naturally occurring kaempferol glycoside SL0101 (1a) and its analogues 1b-e, as well as their enantiomers, have been achieved in 7-10 steps. The routes rely upon a diastereoselective palladium-catalyzed glycosylation, ketone reduction, and dihydroxylation to introduce the rhamno-stereochemistry. The asymmetry of the sugar moiety of these kaempferol glycosides was derived from Noyori reduction of an acylfuran. An acetyl group shift from an axial (C-2) to equatorial position (C-3) under basic conditions was also described. [reaction: see text]
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Affiliation(s)
- Mingde Shan
- Department of Chemistry, West Virginia University, Morgantown, WV 26506, USA
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Smith JA, Maloney DJ, Clark DE, Xu Y, Hecht SM, Lannigan DA. Influence of rhamnose substituents on the potency of SL0101, an inhibitor of the Ser/Thr kinase, RSK. Bioorg Med Chem 2006; 14:6034-42. [PMID: 16723233 DOI: 10.1016/j.bmc.2006.05.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2006] [Revised: 05/04/2006] [Accepted: 05/04/2006] [Indexed: 10/24/2022]
Abstract
We have previously reported the isolation of kaempferol 3-O-(3'',4''-di-O-acetyl-alpha-l-rhamnopyranoside) from Forsteronia refracta [Xu, Y.-M.; Smith, J. A.; Lannigan, D. A.; Hecht, S. M. Biorg. Med. Chem.2006, 14, 3974-3977.]. This flavonoid glycoside, termed SL0101, is a specific inhibitor of p90 ribosomal S6 kinase (RSK) with a dissociation constant of 1 microM. In intact cells, however, the EC50 for inhibition of RSK activity is 50 microM, which suggests that the efficacy of SL0101 could be limited by cellular uptake. Therefore, we investigated the possibility of developing a more potent RSK inhibitor by synthesizing SL0101 analogs with increased hydrophobic character. The total syntheses of kaempferol 3-O-(3'',4''-di-O-butyryl-alpha-L-rhamnopyranoside) (Bu-SL0101) and kaempferol 3-O-(2'',3'',4''-tri-O-acetyl-alpha-L-rhamnopyranoside) (3Ac-SL0101) were performed. The IC50 for inhibition of RSK activity in in vitro kinase assays for the analogs was similar to that obtained for SL0101. 3Ac-SL0101 demonstrated the same remarkable specificity for inhibiting RSK activity in intact cells as SL0101; however, Bu-SL0101 was not completely specific. 3Ac-SL0101 was approximately 2-fold more potent at inhibiting MCF-7 cell proliferation compared to SL0101 and preferentially decreased MCF-7 cell growth, as compared to the growth of the normal human breast line, MCF-10A. Thus the discovery of 3Ac-SL0101 as a more potent RSK-specific inhibitor than SL0101 should facilitate the development of RSK inhibitors as anti-cancer chemotherapeutic agents.
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Affiliation(s)
- Jeffrey A Smith
- Center for Cell Signaling, University of Virginia, Charlottesville, VA 22908, USA
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